Keeping Shaders in Memory
I discovered an answer to this:
Preferences/System/Memory &amp; Limits/Texture Time Out
I had this set as default to 120 (seconds I am presuming). It is possible to set it to 0 so that they are kept in memory.
What would be nice is if it were possible to load or unload textures manually. Often, we are working on lighting and textures for a while and then sometimes modelling and animation.